Malaysia is to keep a group of suspected Muslim militants under detention for a further two years, officials said on Tuesday.

The suspects have already spent two years in custody under the country's controversial Internal Security Act, which allows for detention without trial.

Their cases came up for review on Tuesday, but Home Minister Abdullah Ahmad Badawi signed orders to keep them behind bars after deciding they were still a threat to national security, an official said.

The son of the spiritual leader of Malaysia's large Islamic party PAS is one the detainees.

Jemaah Islamiah links

The nine men were seized in August 2001, weeks before the 11 September attacks on America.

They were arrested in connection with a botched bank raid, which led police to a little-known Islamic organisation called the Kumpulan Militan Malaysia (KMM).

According to Malaysian authorities, subsequent investigations revealed that this group was linked to Jemaah Islamiah (JI) - a regional Islamic group said to have ties with al-Qaeda, and blamed for a string of recent bomb attacks including the Bali blasts last October.

They are among about 90 suspected Muslim militants who have been detained by Malaysia in the past two years.

Last week, Pakistan arrested 13 Malaysian students as well as the brother of suspected JI operations chief Hambali, in the continuing hunt for regional extremists.

All the suspected militants in custody in Malaysia are being held under the country's Internal Security Act (ISA), which allows police to hold suspects for 60 days, after which they can be jailed without trial for periods of two years on the authority of the Home Minister.

This group is the first whose cases have come up for review. According to the BBC's correspondent in Kuala Lumpur, extending their detention seems to signal that the government is sticking to its tough line.

Human Rights Watch urged the Malaysian authorities on Tuesday to "give the detainees their day in court or release them".

"While there may well be some people in custody with ties
to violent groups, they should be given a fair trial under
Malaysia's criminal law, instead of disappearing into the
black hole of the ISA," said Brad Adams, executive director of
the group's Asia division.

Among the detainees is Nik Adli Nik Abdul Aziz, son of Nik Aziz Nik Mat, the spiritual leader of the country's main opposition group PAS.

Several other detainees are also members of the party, and there is concern that the government's actions are motivated by political rather than security reasons.

But the government has rejected criticism that its security laws are overly harsh, pointing to the treatment of prisoners by the US at Guantanamo Bay and tough anti-terror laws introduced by Western countries in the last two years.